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"pfjw@aol.com" <peterwieck33@gmail.com>: Aug 09 06:21PM -0700 This is water for your house. That means that it is a critical function.   Cut the crap about what you 'can' or 'cannot' do. It is only money, and you owe it to yourself and any (possibly unfortunate) family as may also need reliable water on rare occasion. Start over, do it right and sleep well. Do anything else, and be prepared for the worst possible scenario.   Keep in mind that this forum exists so that the uninformed may provide the least appropriate, most complicated, least reliable solutions for established problems with established (and reliable) solutions such that the requester of such information may be relieved of taking responsibility to do the right thing in the first place.   Peter WIeck Melrose Park, PA

"pfjw@aol.com" <peterwieck33@gmail.com>: Aug 09 06:26PM -0700 Line drop. Bullshit. Use #6 copper UF cable, and the line-drop for a 400-foot run is 2.53 volts at 8 amps (1920 watts).   Repeat: cut the BS and do it right.   Peter WIeck Melrose Park, PA   https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=1.296&voltage=240&phase=ac&noofconductor=1&distance=400&distanceunit=feet&eres=8&x=68&y=10

Paul Drahn <pdrahn@jodeco.com>: Aug 10 08:09AM -0700 > https://www.mpja.com/download/33984-86RLData.pdf > Thanks, > Eric   MY well is powered from the shop line as well as your well. The shop/garage is on a separate 100 amp line from the service point. The house is a 200 amp line from the same service point.   Why do you need to change the source of service to the pump?   Paul

etpm@whidbey.com: Aug 10 09:39AM -0700 On Mon, 10 Aug 2020 08:09:59 -0700, Paul Drahn <pdrahn@jodeco.com> wrote:   >house is a 200 amp line from the same service point.   >Why do you need to change the source of service to the pump?   >Paul The house has a generator for when the power goes out. The shop does not. This is why the change in power source. Eric

Jeff Urban <jurb6006@gmail.com>: Aug 09 07:21PM -0700 I have a question, of course I cannot compel you to answer it but you definitely won't if someone doesn't ask.   Where do you get this education ? Don't gimme this "I graduated in 19XX" shit, you are on top of near cutting edge tech here. None of this shit existed probably the last time you graduated anything.   Is it independent research ? Little courses or seminars from your clients ?   And on communications, damn. You are on a different planet than me. I know what a yagi antenna is but not how it works. I got a technical paper on the phased arrays in cell towers and believe it or not I understand the principle. But you could probably program it, where do you get that knowledge ?

legg <legg@nospam.magma.ca>: Aug 09 10:33PM -0400 On Sun, 9 Aug 2020 19:21:25 -0700 (PDT), Jeff Urban   >Where do you get this education ? Don't gimme this "I graduated in 19XX" shit, you are on top of near cutting edge tech here. None of this shit existed probably the last time you graduated anything.   >Is it independent research ? Little courses or seminars from your clients ?   >And on communications, damn. You are on a different planet than me. I know what a yagi antenna is but not how it works. I got a technical paper on the phased arrays in cell towers and believe it or not I understand the principle. But you could probably program it, where do you get that knowledge ?   Reading and comprehension x n years.   RL

Jeff Liebermann <jeffl@cruzio.com>: Aug 09 08:47PM -0700 On Sun, 9 Aug 2020 19:21:25 -0700 (PDT), Jeff Urban   > I have a question, of course I cannot compel you to answer it but you definitely won't if someone doesn't ask.   Well, when you learn to spell my name correctly, I might be a bit less abrasive.   > Where do you get this education ?   <https://www.linkedin.com/in/jeff-liebermann-151823/> I used to have my resume on LinkedIn, but now I can't find it. Argh... it looks and smells like Facebook.   > Don't gimme this "I graduated in 19XX" shit, you are on top > of near cutting edge tech here. None of this shit existed > probably the last time you graduated anything.   Actually, I'm very much behind the times in many areas. I mostly gave up on working in RF in about 1983. I switched to computer repair, which I thought was more interesting and less demanding. I continued to do RF design up to about 2010. However, all the work was doing damage control on someone else's mess, to filling in when someone bailed out in the middle of a project. As of the end of the month, I'll be retired (I'm 72) and out of the computer consulting biz. I'm shutting down the office, and moving all the junk home. After 30 years, it hurts, especially when I recycled as eWaste a dumpster full of computers and PCBs. I'm not sure what I'll be doing next month. I hate to admit it but technology is my life. Somewhere along the line, I forgot to get married and have deductions.   So, you're wondering how I managed to learn all this stuff. Same as most people. I read, I watch YouTube videos, I try to understand, I build things, I repair far too many things, I design a few things, and so on. Learn by Doing was the college motto. It takes a lifetime of doing to get to where you think I'm at so don't expect instant enlightenment. I've also taught classes, answered far to many tech questions on Usenet, gotten involved in virtual companies, and done some management. In other words, I haven't done just one thing that made me so cutting edge. I tried many things, understood how they related to each other, failed at some, did well at others, and made some money doing it.   If want to do the same, I suggest you concentrate on learning how things work. Once you learn that, you can fix or design anything. Incidentally, by work, I mean how anything works, including politics, banking, automobiles, computers, investors, and other things you're likely to encounter.   >Is it independent research ? Little courses or seminars from your clients ?   I've never taken a formal class in anything beyond what I took in college and teacher preparation. I sometimes attended seminars to meet the people doing the work, not to hear the talk. I tried to attend trade shows, user groups meetings, and a few too many parties, again to meet the people involved, and not so much to learn anything technical. For tech, it was a mixture of "Learn by Destroying", reading, getting my hands dirty, more reading, etc. Instead of hearing lectures, I give them. I learn far more by researching a topic and explaining it to a room full of sharks ready to pounce on any mistake I might make, than I do from being spoon fed the same information by a speaker where English is their 3rd language.   >And on communications, damn. You are on a different planet than me.   Hardly. I just have had more time to absorb the subject and work with it. There are many areas in communications where I'm severely lacking. However, I am willing and able to fill in those holes when needed.   >I know what a yagi antenna is but not how it works.   <https://www.google.com/search?q=how+a+yagi+antenna+works> Read, think, build, fail, and then ask.   >I got a technical >paper on the phased arrays in cell towers and believe it or not I >understand the principle.   Good. Then hang around the RF related newsgroups and forums and try to ANSWER someone's questions about phased arrays and cell tower antennas. While writing your reply, you'll probably discover that there's something lacking in your explanation, which will send you off to Google to search of the missing parts of the puzzle. When your explanation is posted, you will likely be attacked by someone who found a mistake, disagrees with your explanation, or has a better explanation. You will then worry that your reputation is now ruined, and that nobody will ever believe anything that you have written or will write. Fine. Admit your mistake, post a correction, thank the person who found your mistake, and add something of value to the discussion. With that, you've redeemed your reputation and probably learned something you'll never forget. Above all, never post or write anything that you would not consider worth reading.   >But you could probably program it, where >do you get that knowledge ?   Well, I certainly didn't learn antennas overnight. It does take time. As for antenna knowledge, I've built a few antennas over the years, which taught me quite a bit about the characteristics of some antennas. I've also done some antenna modeling (and reverse engineering), mostly with 4NEC2: <http://www.learnbydestroying.com/jeffl/antennas/>   Good luck.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: Aug 10 11:45AM +0200 On 10.08.20 4:21, Jeff Urban wrote:   > Where do you get this education ? Don't gimme this "I graduated in 19XX" shit, you are on top of near cutting edge tech here. None of this shit existed probably the last time you graduated anything.   > Is it independent research ? Little courses or seminars from your clients ?   > And on communications, damn. You are on a different planet than me. I know what a yagi antenna is but not how it works. I got a technical paper on the phased arrays in cell towers and believe it or not I understand the principle. But you could probably program it, where do you get that knowledge ?   My education trained me to use my brain. Taught me how and why science worked. Taught me how components and electricity worked. Then working at a research institute kept all that fresh and useful. And was fun.

Andy Burns <usenet@andyburns.uk>: Aug 10 11:29AM +0100 Jeff Urban wrote:   > Where do you get this education ?   Presumably from destruction?

Jeff Urban <jurb6006@gmail.com>: Aug 10 06:15AM -0700 I guess I forgot the extra "N", sorry. i can't rememebr everything.   >Actually, I'm very much behind the times in many areas. I mostly >gave up on working in RF in about 1983. I switched to computer >repair,   You don't seem to be behind to me.   >As of the end of the month, >I'll be retired (I'm 72) and out of the computer consulting biz.   You might want to get out of California, it is getting bad there. Even if you are a liberal, sanctuaries for criminal invaders ? Shit on the streets of Frisco ? You stay there it is coming to you and personally I think you deserve better.   >However, all the work was doing >damage control on someone else's mess   There's something you don't have to explain to me.   >moving all the junk home   Just how big is your house ? I have seen pictures of your shop. With all that, give them notice now that you'll be out by April or so.   >So, you're wondering how I managed to learn all this stuff. Same >as most people. I read, I watch YouTube videos, I try to >understand, I build things, I repair far too many things, I design >a few things, and   So you are largely an autodidact. [So am I, but it appears you got greater challenges to meet in life and thus went farther.     >so on. Learn by Doing was the college motto. It takes a lifetime >of doing to get to where you think I'm at so don't expect instant >enlightenment.   "Instant" is the bane of the human race.   >I mean how anything works, including politics   I have become quite the student of politics. Never was before but we are in very interesting times and November is a crossroads. I do not watch the news, I have sources that are better than their sources sources. Some info I get before AP. Some.   >Good. Then hang around the RF related newsgroups and forums and >try to ANSWER someone's questions about phased arrays and cell >tower antennas.   I doubt I could ANSWER much. I understand the theory of operation, you take and retune certain antenna elements to produce a directional pattern due to the phase shift. From what I have read they can get within ten feet of you without GPS. The system is designed to conserve power, both theirs and yours. I can only imagine the software that runs that shit.   >You will then worry that your reputation is now ruined   No, in that field I have no reputation to ruin for one. And I have "Stand corrected" and retracted when proven wrong. I don't mind people tearing me up, I learn more that way.   >Well, I certainly didn't learn antennas overnight   I did - just stick a piece of wire on it. It is not like I am totally unfamiliar with RF. In fact if a client shows up and his FM needs alignment and the IF does not use ceramic filters I ask "Would you like narrow band or wide band ?". You know what that means but I splain it, narrow band gives you better sensitivity, wide band gives you less distortion. Many will want it like it came new, and usually it is still close, all that needs it is the detector and the front end. And don't offset the front end for bandwidth, the Q is already low and it won't help anything. Usually it has a smooth rolling off 5MHz bandwidth, just keep the friggin image frequency out, which on US FM occurs at 21.4MHz, right ?   Nobody taught me that, I thunk my way through it.   I meant what I said about getting the fuck out of California. You claim to know politics then you know they are getting more and more radical by the day. At your age you can't fight, even having a gun, for some people it is not a good idea if they are too infirm to hold on to it.   California is getting crazy and if I read my Liebermanns right you probably do not want to be a part of that. This protesting, bags of piss and burning down pizza places or whatever, that is a young person's game.   Actually, you could come to Ohio. You got money and don't say you don't. You probably have the first dollar. Low taxes, low property prices, even food is cheaper here.   The government doesn't do all that much but I see that as a good thing. Just stay away from me. And you can have guns here, whole cabinets full of them. I got a friend who has a gun safe so big you could fit like 12 bodies in there if you stack them right. Of course the guns would have to come out... They are not up your ass about everything here except in certain cities, DO NOT go to Independence, Ohio. They make the NAZIs look like George Washington. The cops came because someone had a jet ski in the driveway.   Jack and I went to change a hot water tank for a buddy of ours out there. About to carry it out the the tree lawn he is "NO NO NO !". We either took it with us, which we did, or just leave it in the house and he could deal with it later. But if it is on the tree lawn the cops and inspectors come, they want to see a permit, well the guy needed hot water in the morning and your permit office was close, so he should not shower for work ? They don't give a shit about the consequences of the laws they make.   In California one area you got fined if your lawn turned brown. You also got fined for watering it. So a company pops up and paints your grass. What's more, they tried that shit on the federal government, How about "Would you like to go back to dirt roads motherfuckers ?".   You have not expressed much political. Liberals do so I will guess you lean at least slightly conservative. If that is the case you really don't belong there.   Perhaps you really like it there so much that you are willing to tolerate the joke they call a government. Or maybe you stuck around because of your clientele.   Enough for now. We will drag this out more later. But I say this, if you are retiring for sure, think about where you want to be.

Jeff Liebermann <jeffl@cruzio.com>: Aug 10 09:03AM -0700 On Mon, 10 Aug 2020 11:29:05 +0100, Andy Burns <usenet@andyburns.uk> wrote:   >Jeff Urban wrote:   >> Where do you get this education ?   >Presumably from destruction?   Mostly true and only if I could fix it after destroying it.   I attended college at Cal Poly, Pomona. The skool motto was "Learn by Doing". <https://www.cpp.edu/polyadvantage/application-of-knowledge.shtml> Minimal lectures and maximum labs. I didn't just read about what I was learning. I had to work with it and demonstrate some proficiency. Not exactly a college for engineers dabbling exclusively in theory. I probably learned more helping build various Rose Floats than I did from class work. <http://www.learnbydestroying.com/jeffl/pics/jeffl/#RoseFloat01.jpg>   The standard joke was to modify the skool motto to "Learn by Destroying". As I blundered my way through various jobs and businesses, I realized how true that was. One really must tear something apart, probe around the insides, deduce how it works, and occasionally find some design mistakes. Only after you have broken something, and then fixed it, can one truly say they understand how it works. When it came time to select a suitable domain name, LearnByDestroying.com was my 2nd choice.   Since then, I've made it a point of tearing things apart and looking inside. Sometimes, I do that before checking to see if it worked. I rarely read the instructions as it's much more fun to figure things out for myself. There's nothing more frustrating to me than a device that is designed to discourage inspection and repair. When doing a design, I often inspect and reverse engineer the competitors products to see what they had done. Sometimes, I get useful insights. More recently, I'm finding disgusting junk, marginal design, and pointless cost cutting. Whatever I find, I learn from the mistakes of others. I try not to destroy anything, but sometimes, destructive testing is a necessary and useful evil on the road to understanding.   Note that this doesn't just apply to electronic devices. I use the same methods in mechanical devices, chemistry, adhesives, lubricants, household products, automobile repair, and construction. If I know how it works, I can fix it, build it, and possibly design something better. If something needs to be destroyed along the bumpy road to knowledge, that's the price I pay.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <jeffl@cruzio.com>: Aug 09 09:54AM -0700 >Please is there any gadget/circuit/App that can detect a mobile phone when ; >1. even when the phone is off but the battery is inside.   No. When the phone is turned off, all of the various transmitters (cellular, Wi-Fi, BlueGoof, and NFC) are turned off. It might be possible to detect the NFC (near field communications) resonant circuit at 13.56MHz with something like a "grid dip meter".   >2. When the phone is on   Yes, as long as "airplane mode" is turned off. There are transmissions from the cellular section to the tower to allow the phone to check into the network and establish its presence. If enabled, Wi-Fi and Bluetooth also transmit keep alive signals.   At this time, power-on NFC services (such as Google Pay) intentionally do NOT work on a smarphone unless the phone is turned on and NFC is enabled. However, that might change as NFC begins to encroach on RFID territory: <https://www.xda-developers.com/future-android-smartphones-nfc-to-work-disabled/> Meanwhile, looking for a 13.56MHz tuned circuit might work.   >3. when the battery has been removed   No. Again, the NFC section may not require power to be detectable. <https://en.wikipedia.org/wiki/Near-field_communication> <https://nfc-forum.org/what-is-nfc/about-the-technology/> However, the other transmitters require power to function. Same with the various "find my phone" programs: <https://www.google.com/android/find>   >thank you.   Good luck. The big problem is not detecting whether there is a cell phone present. It's how to identify a particular phone and how to deal with the clutter caused by a multitude of phones in the same area. It might be possible to detect a phone if it was the only phone in the area, but not in a crowd of phones.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

fynnashba@gmail.com: Aug 09 04:07PM -0700 > 2. When the phone is on > 3. when the battery has been removed > thank you.   Thanks to you all. My next problem is after detection, can the phone be zeroed in on? (located)

bob prohaska <bp@www.zefox.net>: Aug 10 01:44AM > deal with the clutter caused by a multitude of phones in the same > area. It might be possible to detect a phone if it was the only phone > in the area, but not in a crowd of phones.   This may be bending the OP's intent a little, but (many) years ago I was led to believe that it was possible to detect semiconductor devices by "illuminating" them with RF and looking for second harmonic scatter. It's merely a "there or not there" test, supposedly used to test secure spaces for for eavesdropping devices. No firsthand experience, alas.   Have I been misled?   Thanks for reading,   bob prohaska

Jeff Urban <jurb6006@gmail.com>: Aug 09 07:05PM -0700 >but (many) years ago I was led to believe that it was possible to >detect semiconductor devices...   I can see that working under certain circumstances, but the limitations would make it not all that useful.

Jeff Liebermann <jeffl@cruzio.com>: Aug 09 07:16PM -0700 On Mon, 10 Aug 2020 01:44:30 -0000 (UTC), bob prohaska >It's merely a "there or not there" test, supposedly used to test secure >spaces for for eavesdropping devices. No firsthand experience, alas.   >Have I been misled?   It's quite real. The principle is still being used in some retail theft prevention tags. The tag has a 900 MHz antenna, diode, and 1800 MHz antenna. When the customer leaves the store, the tag is illuminated by 900 MHz. If the tag is intact, the diode produces a 2nd harmonic, which is re-radiated by the 1800 MHz antenna. A receiver near the 900 MHz transmitter listens for 1800 MHz and sounds an alarm. When the customer pays for merchandise, the checker waves the tag over some kind of induction device, that fries the diode so that it doesn't trigger the alarm as the customer leaves the store.   You could do something like that to detect cell phones. The problem is that if the sensitivity of the receiver was sufficient for such a system to work with most any semiconductor, it would also false trigger anything with electronics inside. It has no way to distinguish between a smartphone and car alarm key fob. It might also trigger on harmonic generated by diodes created by dissimilar metals and corrosion. Such false triggering would probably make it useless. Note that the concept has been extended to passive RFID tags: <https://www.researchgate.net/figure/Harmonic-RFID-concept_fig1_234682635> <https://www.google.com/search?q=harmonic+rfid>   It wouldn't take much to shield a wireless bug from being detected by such a system. The best place to hid a bug is inside something stuffed full of electronics, such as a phone, TV, monitor, keyboard, mouse, etc. If you "sweep" a room looking for diodes, it would be triggered by all these devices, which would then need to be individually disassembled and inspected for tampering.   Drivel: I wonder how such a system would respond to an OLED display in a smartphone, which has at least one diode per pixel.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <jeffl@cruzio.com>: Aug 09 07:43PM -0700 > My next problem is after detection, can the phone be zeroed in on? (located)   No, if you're asking if the GPS in the phone can be interrogated.   No, if you're trying to do direction finding. The likely problem is that with the power turned off, the only thing that might be usable is to direction find on the RF energy being absorbed by the 13.56 MHz NFC loop antenna. I can think of few ways that might be possible, but the range will be very small, and due to the low frequency, accuracy very poor.   Yes, if the phone is transmitting on cellular, wi-fi, or Bluetooth frequencies. Unfortunately, there is no idea system. The problem is that there are other users also transmitting on cellular and Wi-Fi frequencies. You not know which frequency is being used by the phone being located and you don't know when it will be transmitting. Instead of a nice clean direction indication, you'll see a jumbled mess of users, frequency hoppers, spread spectrum junk, collisions, and interference. You could build something that would work under idealized conditions, but in a crowded RF polluted environment, it will be very difficult to use.   Offhand, I think the best approach is also the simplest. Build a rotating directional antenna on the frequencies of interest. A polar display will show both the bearing and a radial line for the signal strength. In other words, an AM (amplitude modulated) receiver. Use an SDR spectrum analyzer for finding the signals coming from the phone, and then switch the SDR receiver to the frequency of interest for direction finding. Such an arrangement is far from perfect and there will be situations where it doesn't work, but it's the closest and easiest DF system to build.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

bob prohaska <bp@www.zefox.net>: Aug 10 03:22AM > distinguish between a smartphone and car alarm key fob. It might also > trigger on harmonic generated by diodes created by dissimilar metals > and corrosion. Such false triggering would probably make it useless.   You mentioned 13.56 MHz being used by cellphones. Combined with the 2.4GHz (or maybe 5, on a modern cellphone) would it not be possible to illuminate with both frequencies and then look for harmonics? That still isn't perfect, but it'd help exclude some false positives.     > individually disassembled and inspected for tampering.   > Drivel: I wonder how such a system would respond to an OLED display > in a smartphone, which has at least one diode per pixel.   Wouldn't that sort of setup have a relatively low Q with fairly uniform response over a wide frequency range? Perhaps I'm suggesting not looking for junctions specifically, but for resonant circuits connected to antennas that must be exposed for the device to function. Obviously no help if the phone is under a tinfoil hat, 8-).   One question is power levels; if the interrogation signal starts melting chocolate bars to get a recognizable return it's likely a bad idea....   Thanks for replying!   bob prohaska

Jeff Liebermann <jeffl@cruzio.com>: Aug 09 09:16PM -0700 On Mon, 10 Aug 2020 03:22:41 -0000 (UTC), bob prohaska >2.4GHz (or maybe 5, on a modern cellphone) would it not be possible >to illuminate with both frequencies and then look for harmonics? That >still isn't perfect, but it'd help exclude some false positives.   The system of illumination you propose relies on three circuit elements being present. There has to be a tuned circuit resonant at the illumination frequency, a non-linear element (diode) to produce the harmonics, and a reasonably efficient radiator of the 2nd (or 3rd) harmonic signal. The tuned circuit is present in the 13.56 MHz loop found in smart phones: <http://www.antenna-theory.com/definitions/nfc-antenna.php> However, there's no diode or transmit (transponder) antenna in the phone. So, that won't work. (The grid dip meter idea might work because it doesn't need a diode or transmit antenna).   For the Wi-Fi/BT frequencies, there's also no tuned circuit, so those also won't work. In the bad old days of analog phones, there were cavity resonators tuned to the cellular operating frequencies, but those haven't been used in smartphones for probably 20 years.   >for junctions specifically, but for resonant circuits connected to antennas >that must be exposed for the device to function. Obviously no help if the >phone is under a tinfoil hat, 8-).   Well, diodes don't have a Q factor, so that's not relevant. The various resonant circuits and antennas all have a Q. Broadband devices are inherently low Q, so they won't be very efficient for detection and retransmission. The 13.56 MHz loop could have been designed with a fairly high Q, except that body capacitance would ruin the tuning. So, my guess(tm) is that it's also a low Q device. The various RF elements might all be very wide band, but that doesn't offer much if the signal levels and efficiencies are so low as to be useless.   >One question is power levels; if the interrogation signal starts melting >chocolate bars to get a recognizable return it's likely a bad idea....   That was Percy Spencer, inventor of the microwave oven, who noticed that a chocolate bar melted in his pocket while working on a radar set for Raytheon. <https://en.wikipedia.org/wiki/Microwave_oven#Discovery> At the present state of the art, illuminating a smartphone with that level of RF will likely destroy the phone before it melts the chocolate. FCC 15.247(b)(2) limits tag readers to 1 watt RF output: <https://www.law.cornell.edu/cfr/text/47/15.247>   >Thanks for replying!   Y'er welcome.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

etpm@whidbey.com: Aug 09 03:41PM -0700 I have been looking online but there seems to be, for a lot of the antennas, an assumption of prior knowledge. That I don't have. What I want to do is survey some of my property line. Mainly so I know about where it is because about 25% of the length is ambiguous. I can pay a surveyor to do the job but it would cost about 4 thousand bucks. Of course a proper survey would be more accurate and precise but I don't need that accuracy or precision. So I am looking for an antenna that could be either plugged into a handheld GPS or a tablet. And I don't know even where to start. I don't know how much gain I need. Or sensitivity. Maybe there is already a han held unit that is good enough all by itself. Our property is heavily wooded with a mix of conifers and deciduous trees, mostly alders. In the summer the trees make my hand held GPS unit useless. It is an older unit so I will be buying a modern one that will hopefully be better. I live north of Seattle and the satellites seem to be mostly in the southern sky, if that makes any difference to any antennas. I would like to keep the total expenditure for antenna and GPS unit to less than $400.00 I have looked into renting a surveyors GPS unit but have not been able to find anyone in the greater area who rents them. Can anybody help? Thanks, Eric

Jeff Liebermann <jeffl@cruzio.com>: Aug 09 06:00PM -0700 > I have been looking online but there seems to be, for a lot of the >antennas, an assumption of prior knowledge. That I don't have.   Yep. The basic assumption is that the user knows the difference between a GPS receiver and a GPS antenna.   > What I want to do is survey some of my property line. Mainly so I >know about where it is because about 25% of the length is ambiguous.   There are numerous Android applications useful for surveying. I use "Mobile Topographer" (free) for accurately locating antenna towers for generating coverage maps: <https://play.google.com/store/apps/details?id=gr.stasta.mobiletopographer> <http://applicality.com/projects/mobile-topographer-free/> Basically, the way these work is to place the phone at a given location and run the program for some length of time. The program then averages many GPS position reports producing improved accuracy. The longer it runs, the more accurate the position. This is an alternative to using DGPS (differential GPS) correction data to post process recorded positions, which is what the surveyors normally provide.   For fun, I just fired up the program inside my house on my desk next to a large picture window, which is not a great location for surveying. On startup, it settled down to 12.0 meter accuracy. After about 15 mins running, accuracy improved to 1.84 meters.   The problem with using averaging is that if your property boundary position involves a court or planning department case, they are unlikely to accept your amateur surveying as accurate. They want data from a licensed surveyor that includes corrections from existing benchmarks to deal with ground slipage, earthquakes, and continental drift. If your county has online GIS data available, you can see the type of maps that the county might be expecting. What the smartphone GPS and averaging method buys you is a trial run to determine if it's worth paying for a professional survey and whether you will have a chance before a court or board. If there's a dispute with a neighbor, it might also be sufficient to convince the neighbor to cooperate.   If you decide to go this route, make sure you use a fairly up to date smartphone that can do GPS, WAAS, GLONASS, and possibly other satellite navigation satellite systems. The more satellites, the more accurate your position.   Altitude accuracy can be marginal depending on your location. For example, if you're measuring the surveying the bottom of a canyon, you'll have problems.   If you're doing to spend an afternoon doing this, you'll find that the GPS can really run the smartphone battery down. I suggest having one of the larger battery banks or 12V charger available.   Make sure you use the correct datum. WGS84 is the most common, but there are still people who want NAD27.   There are YouTube videos on surveying with a smartphone: <https://www.youtube.com/results?search_query=android+surveying+app> and other apps that might be more suitable: <https://www.google.com/search?q=android+surveying+applications>   If you want to do averaging with a laptop and an external (USB or serial) connected GPS, look at software from: <https://www.visualgps.net> I use Visual GPS View ($5) and Visual GPS Legacy (free), which will both generate a location plot, which you can then eyeball for a more accurate position.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

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